WO1994026184A1

WO1994026184A1 - Process and device for thermally obliterating biological tissues

Info

Publication number: WO1994026184A1
Application number: PCT/DE1994/000554
Authority: WO
Inventors: Jürgen BEUTHAN; André ROGGAN; Gerhard Müller
Original assignee: Laser-Medizin-Zentrum Gmbh, Berlin
Priority date: 1993-05-14
Filing date: 1994-05-11
Publication date: 1994-11-24
Also published as: US6143018A; EP0697840A1; DE59410356D1; EP0697840B1; DE4403134A1

Abstract

A process is disclosed for thermally obliterating biological tissues by laser radiation introduced into the tissue by means of an optical waveguide. The laser radiation is scattered by means associated with the radiation output surface of the optical waveguide. A biocompatible, medium to highly visquous liquid which does not substantially absorb the laser radiation but scatters it, is injected into the tissue, forming a scattering fluid deposit around the radiation output surface which is not separated from the tissue and which allows the tissue to be heated in a controlled manner.

Description

Method and device for thermal sclerotherapy of biological tissue

Description

The invention relates to a method of the type specified in the preamble of claim 1 and an apparatus for performing the method.

It is known that laser radiation is guided by means of optical waveguides and the radiation thus transmitted ent neither introduced transluminally or transcutaneously into biological tissue directly by means of the optical waveguide, or its distribution function additionally influenced in a targeted manner by further measures, for example via special catheters or endoscopes, and the radiation specifically applied in this way for inducing thermal or photo ¬ chemical necrosis can be used. It has been common practice since the mid-1970s to introduce neodymium: YAG laser radiation into biological tissue in this way and to use the absorption of this radiation that occurs in the tissue to heat the tissue-end areas and thus to cause coagulation necrosis.

Due to the fact that the optical fibers used have active diameters between 200 and 600 μm, a very high power density results at the fiber / fabric interface even with low laser output powers. The carbonization threshold of the tissue is therefore exceeded very quickly, with the result that the emerging laser radiation is additionally absorbed by the carbonate and can no longer penetrate in accordance with the optical coefficient typical of the tissue. Even the most experienced surgeon only succeeds in producing coagulation necrosis with a diameter of 5 to 7 mm, which is usually accompanied by carbonization of the tissue touching the end of the fiber.

In terms of surgery, the transcutaneous introduction of the optical fiber, the so-called "bare-fiber", is usually carried out with puncture sets, ie with metallic cannulas and trousers. Karen. The transluminal application continues via suitable flexible catheters or endoscopes.

US Pat. No. 5,169,396 describes a method for interstitial laser therapy, the basic features of which are characterized in that direct contact of the fiber end face with the tissue is prevented by first placing a liquid depot with a biocompatible liquid absorbing the laser radiation at the end of the puncture cannula becomes. Thus, primarily the fiber-tissue interface is no longer heated, but rather the light-absorbing liquid, which in turn heats the surrounding tissue via heat conduction.

Although this procedure avoids the primary carbonization at the end of the fiber, it has the decisive disadvantage that the energy is only transported into the tissue by heat conduction and thus, in view of the large heat sink of the surrounding tissue, leads to very limited coagulation necrosis. Furthermore, the method has the major disadvantage that the pigments or chromophoric groups of the liquid absorbing the laser radiation also decompose photochemically or thermally at the radiation powers used and the resulting power densities at the fiber end and thus trigger uncontrollable side effects .

In an arrangement known from DE 40 41 234, the problem of carbonization at the fiber-fabric interface is attempted to be solved by the fiber end being specially prepared in such a way that the laser radiation is no longer directs prograd out of the fiber with a very small exit aperture, but is gradually sprinkled radially out of the fiber over a longer distance. The distribution of the laser power on the surface of the applicator is further evened out by further measures which increase the radial scatter, such as the provision of a scattering dome.

Although these measures largely achieve the goal of introducing the laser radiation into the tissue as homogeneously as possible, the technological expenditure for the preparation of the fiber end and possibly a high-temperature-resistant but flexible sheath catheter are considerable. Another disadvantage of this laser scattered light applicator with an enveloping catheter is that the tissue layer adjacent to the catheter naturally heats up and coagulates particularly quickly due to the absorption of light, and it has been shown that the coagulated tissue has a significantly poorer transmittance for directional optical radiation in the wavelength range having.

DE 42 11 526 AI and DE 42 37 286 AI specify a device which works with active cooling within the sheath catheter, the coolant simultaneously taking on the task of additionally dispersing the laser light. In a modification it is provided that biocompatible cooling fluid can escape from the catheter through preformed pores in the sheath catheter, thus avoiding carbonization and thus also adherence of adjacent tissue. In this arrangement, laser power of more than 5 W, typically 10 to 1 W, can be used by the active cooling, but at the same time, part of the applied energy is dissipated unused due to the cooling. Since the biocompatible liquid is rapidly distributed in the tissue, relatively large amounts are also required during a treatment lasting 10 to 20 minutes, which may also lead to stress on the patient. Finally, in this way - as with the aforementioned solutions - only spherically symmetrical treatment zones can be realized. The treatment of elongated, but relatively slim, diseased tissue areas requires multiple application by repositioning in the sheath catheter and leads, for example in the treatment of benign prostatic hyperplasia (BPH), to very long radiation times per prostate flap of up to 40 min.

The invention is based on the object of developing a method of the type mentioned at the outset in such a way that tissue obliteration using efficient use of laser radiation and stray liquid is made possible in treatment zones which are as large as possible and also non-spherically symmetrical, and to provide an apparatus for carrying out the method.

This object is achieved by a method having the features of claim 1 and an apparatus having the features of claim 14.

The invention includes the idea that in the vicinity of the exit surface of the laser radiation from one of its line serving optical waveguide into the tissue to be obliterated to create a scattering range that is essentially stable during the treatment and that is essentially stable during treatment, in which essentially no absorption takes place, but only as diffuse a scattering of the laser radiation as possible. A scattering fluid depot made of a sufficiently viscous liquid or a liquid mixture which is essentially transparent in the wavelength range of the laser radiation serves this purpose.

Since the fluid does not absorb the laser radiation and the scattering processes represent pure phase scattering, the fluid does not heat up significantly, as a result of which coagulation at the radiation exit surface to the tissue is suppressed over a long period of time, measured in terms of the total irradiation time.

The method according to the invention is based on the surprising finding that by avoiding primary coagulation at the edge zone of scattering liquid / tissue, the laser radiation which diffuses diffusely in the scattering liquid can penetrate into the tissue by a factor of 2 to 3, and thus is absorbed there in a significantly larger volume and this volume is heated up. After an irradiation time of several minutes, a concentric coagulation zone then occurs, which prevents further pure radiation transport into the depth of the tissue, but at the same time, due to the increased temperature, a very large volume of heat source for utilizing the heat conduction for further thermal desolation of the surrounding tissue. The tissue surrounding the liquid depot is only coagulated towards the end of the treatment by increasing the radiation power of the laser and thus indirectly leads to further heating of the cooling liquid, so that even after the laser has been switched off, the liquid depot introduced and the massive thermal coagulation front set up again a heat source is present which, on the other hand, thermally damages surrounding tissue via heat output also in the subcoagulative area according to the Arrhenius integral. When the procedure is carried out according to the method, diameters of coagulation zones of up to 3 cm can be achieved. In addition, the subcoagulative, hyperthermic influence due to heat conduction results in a further necrosis with an additional radius of approximately 5 to 7 mm, so that a total of necrosis centers of up to can be set to 4 cm in a controlled manner.

The disadvantages of using a metallic cannula described in US Pat. No. 5,169,396 are avoided in an advantageous manner by using a biocompatible cannula material that does not absorb the laser radiation to introduce the optical fiber and the scattering cooling liquid into the tissue. Variants of the thermoplastic PTFE family, polycarbonates, variants of the HDPE and certain polyurethane are suitable for this.

The surgical procedure is chosen so that access to the center of the tissue area to be obliterated is first found via a probing needle, this procedure being able to take place under simultaneous X-ray or ultrasound control. Then be over this Depending on the size of the necrosis focus to be placed later, one or more dilators are guided, the last of the dilators being identical to the cannula that later guides the laser beam. The biocompatible phase-scattering fluid is then introduced into the tissue via this plastic dilator, which is open at the end.

The cannula used is expediently designed such that it consists of essentially two subassemblies, one of which is the puncture cannula itself, which is to be introduced via a probing needle, and the second of which is a fluid-tight Y to be attached to this puncturing cannula after removal of the probing needle Represents piece via which the fluid scattering the laser light can be injected on the one hand and on the other hand the light waveguide guiding the laser light can be fixed in a pre-adjusted manner and can be axially advanced in a defined manner by means of a displacement mechanism.

It is of particular importance for the method that the fluid has a viscosity adapted to the particular treatment situation, so that a spatially suitably defined liquid depot is maintained over a sufficiently long irradiation time. Therefore, common biocompatible fluids such as physiological saline are excluded, since they have such a low viscosity that during the typical treatment times of 10 to 20 minutes in the tissue types such as parenchyma, muscle, prostate, etc., which are particularly suitable for this type of therapy ml of liquid would be needed to maintain a depot. This can be avoided by choosing a suitable viscosity of the fluid. The fluid can easily and inexpensively consist of a mixture of 0.1 to 2 parts of oil, 10 to 50 parts of water and 50 to 80 parts of glycerin, the respective sum of parts being 100. In a preferred embodiment, an oil-water-glycerine suspension is used, which has the following mixing ratio: 80% glycerin, 18% water and 2% suspended oil droplets.

Furthermore, a mixture of 1 to 30 parts of water and 70 to 99 parts of methyl cellulose - preferably methyl cellulose, mixed with a few percent of physiological saline solution - can be used.

Finally, a mixture of hyalaronic acid and intralipid can also be used.

Depending on the size and geometric shape of the depot, the numerical aperture of the optical fiber must be selected. Good results are achieved with numerical apertures between 0.2 and 0.6. The use of an increased numerical aperture makes it possible to use diode lasers at approximately 800 nm as an energy source in a simple manner.

In an advantageous embodiment, the liquid consists of an essentially transparent and a strongly light-scattering component, and the components are injected into the tissue by means of a concentrically double-lumen cannula in such a way that the transparent component passes over the inner and the strongly light-scattering component are introduced via the outer lumen so that the highly light-scattering component envelops the transparent component.

The transparent component can contain glycerin and water, preferably in a mixing ratio of 80:20, and the strongly scattering component can contain oil and water, preferably with 1 to 5 parts of oil in 100 parts of the mixture.

In a structurally simple further development of this embodiment, the laser radiation can be introduced into the tissue via the liquid column of the transparent component in the inner lumen, which also serves as an optical waveguide, the radiation of the laser light possibly also via an unsteady liquid column - that is, during liquid is still injected - can take place.

To optimize the radiation input into the fluid depot, after the liquid has been injected and the depot has been formed, the optical waveguide can be displaced into the depot by a predetermined amount in the distal direction.

To form elongated treatment zones, the scattering fluid depot is formed in an elongated, in particular essentially ellipsoidal or cylindrical shape, and / or an optical waveguide arrangement with an emission surface shaped in this way is used.

In an advantageous embodiment, this has an optical fiber, the surface of which is in a distal end section has a plurality of areas in the longitudinal direction that follow one another, preferably in the form of a ring, and the end section of which is provided with a protective cover that is transparent to the laser radiation. The matted areas can have a roughness depth and / or a decreasing diameter towards the distal end of the optical fiber.

A cladding tube that scatters the laser radiation — for example, matted — can be provided coaxially with the optical waveguide arrangement.

A protective cover is required because the partial matting or roughening makes the optical fiber extremely fragile. It can be formed in a cost-effective manner by a precision glass or hard plastic cannula which is closed at the end and attached to the mechanically fixed part of the optical waveguide or the cannula. In an expedient, robust design of the catheter or cannula, the protective sheath encloses the entire front part thereof and has openings for the liquid scattering the laser radiation to exit into the tissue.

The course of the temperature field propagation in the treated tissue can expediently be checked by continuous observation of the therapeutic area with a sonography device, echoes additionally occurring depending on the temperature in the area of adjacent blood vessels if the temperature here exceeds a value of 55 ° C. tet and thus the C0 ₂ dissolved in the blood outgasses intermediate and further echoes occur, if one is exceeded Temperature of 95 ° C in the aqueous component of the scattered light fluid intermediate water vapor bubbles arise.

Furthermore, an X-ray contrast medium can be added to the liquid and an X-ray observation of the formation and the condition of the depot can be carried out.

Advantageous developments of the invention are characterized in the subclaims or are shown in more detail below together with the description of the preferred embodiment of the invention with reference to the figures. Show it:

FIGS. 1 a to 1 d are schematic representations for explaining an embodiment of the method according to the invention,

FIG. 2 shows a further schematic illustration to explain a modified embodiment of the method according to the invention and a device for carrying it out,

FIG. 3 shows a schematic detail representation (in cross section) of a further modified device for carrying out the method according to the invention,

FIG. 4 shows a simplified, partially sectioned illustration of a further embodiment,

FIG. 5 shows a detailed illustration of the device shown in FIG. 5, FIG. 6 shows a simplified, partially sectioned illustration of a further embodiment and

FIG. 7 shows a schematic illustration of a method for producing the optical waveguide arrangement used in the embodiments according to FIGS. 4 to 6.

1a to 1d schematically show how the formation of a fluid depot 1 in a body tissue section 2 by means of a cannula 3, the scattering of laser radiation coupled into the depot 1 via a light guide 4 within the cannula 3 and the development of coagulation necrosis 5 run according to an embodiment of the inventive method.

FIG. 1 a schematically illustrates the general procedure when introducing a cannula 3 to carry out the method in the body tissue section 2: First, access to the center of the tissue area to be obliterated is found with a probing wire or a probing needle S. Then a dilator D is inserted via the probing needle S, and finally the cannula 3 via the dilator D. Depending on the size of the necrosis focus to be formed, several dilators can also be set in several stages, and the last one can simultaneously use the laser and / or liquid-carrying cannula for the further steps, as will be described in more detail below.

In the phase outlined in FIG. 1b, viscous scattering liquid was first injected into the tissue 2 via the cannula 3, in which the spatially limited fluid depot 1 was formed. det and started with the coupling of laser radiation into the depot. The photons of the laser radiation are scattered - which is symbolized by jagged arrows - in the quasi-absorption-free scattering liquid of the depot 1 and in the tissue 2. As a result, a first virtual increase in volume during energy transfer into the tissue to be treated is achieved.

In the phase outlined in FIG. 1c, the scattering liquid at the phase boundary 1 'of the depot 1 to the tissue 2 still has a cooling effect, so that a coagulative effect spreads primarily in the depth of the tissue and that which is at a distance from the depot 1 Coagulation layer 5 forms. This means a further virtual enlargement of the active application volume during energy transfer. At the same time, heat conduction causes the quasi-absorption-free stray liquid depot 1 to heat up - there is therefore an energy exchange in the boundary layer area, which is symbolized in the figure by straight arrows.

In the phase outlined in FIG. 1d, the laser radiation is switched off. The heated total volume of the interactive partial volumes causes an optimal expansion of the coagulation necrosis 5 inwards, i.e. to depot 1, as to the outside, i.e. into the depth of the fabric 2 (indicated by arrows thickening towards the end).

This thermal obliteration of tissue volumis is checked by taking advantage of two surprisingly found phenomena: 1. In the case of vital biological tissues which have circulation, a certain amount of C0 ₂ is always dissolved in the blood due to metabolism, it being shown that the solubility product of C0 ₂ in human whole blood is such that above temperatures of 55 ° C there is an intermittent outgassing, which, however, is reversible when the temperature falls below this, ie lower in the tissue volume. This outgassing of CO in the blood can be detected as a change in contrast in a simple manner by the ultrasound system used for the original positioning of the guide needle, so that the 55 ^C C front of the temperature field propagation can be followed in real time in a simple manner.

2. It has also been shown that even with the scattering liquid used, a viscous water-glycerol-oil mixture or water-methyl cell mixture, water vapor is formed at a temperature of about 95 ° C., so that this results in resulting gas bubbles can be easily observed in the ultrasound image in the liquid depot and the laser power can be reduced accordingly so as not to exceed the boiling point. When the solubility product is undershot, the water vapor then immediately goes back into solution and does not represent a risk of embolism.

In a further development, shown schematically in FIG. 2, a cannula 3A inserted into body tissue 2 has a double lumen in the form of an integrated liquid light guide in such a way that it has a coaxial inner lumen 4A which is concentric from an outer lumen. - le ¬

6A is surrounded. The inner lumen 4A serves as a liquid light guide through which an optically transparent component 7A is supplied to the stray liquid. The outer lumen 6A leads a scattering or more viscous component 8A of the fluid to the distal end of the cannula 3A, where a fluid depot 1A forms from both components.

The proximal end of the cannula 3A has a branching element 9A, from which a feed line 10A to the inner lumen 4A and a feed line 11A to the outer lumen 6A extend.

In the puncture phase, the inner lumen serves as a guide shaft for the probing needle for positioning the cannula in the area to be treated. The cannula 3A is positioned by means of a puncture needle, the puncture needle is then removed and the optically transparent fluid component is first applied via the feed line 10A and the inner lumen 4A and then in a second step via the feed line 11A and the outer lumen 6A resulting liquid depot 1A enriched with scattering medium. At the same time, an optical fiber 13A is coupled to the liquid column in the interior of the central lumen 4A of this puncture needle at the proximal end via a pinch seal 12A, which then serves as a liquid light guide when laser radiation is coupled in via the optical fiber 13A.

In a preferred embodiment, a mixture of 80% glycerol and 20% is used as the transparent carrier fluid. Water is used which has a refractive index which is essentially identical to the refractive index of the coupling, laser light-guiding optical fiber. The light-scattering medium consists of a 2 to 5% oil-water emulsion, for example intralipid in a suitable dilution. In this development, there is no longer any contact between the optical fiber and tissue with the risk of carbonization due to the design, but the radiation is introduced into the tissue and the resulting depot is only a priori made by the liquid itself Both components, scattering medium and transparent carrier substance, take place automatically when exposed to laser radiation due to the thermal fluctuations that occur, with the result that the laser light emerging from the liquid light guide does not immediately enter a zone of high scattering, but gradually with increasing radiation depth is more widely distributed in the depot. This leads to an even better introduction of scattered light into the tissue volume to be treated.

FIG. 3 shows a detailed illustration in longitudinal section of the end section of a cannula 3B modified in relation to the cannula 3A according to FIG. 2, which contains an optical fiber 7B that is continuous to the distal end (which is not shown in the figure). An outer lumen 6B, which is connected via a side extension 8B to a device (not shown) for supplying scattering liquid, is closed at the proximal end of the cannula 3B with an axially displaceable, liquid-tight closure cap 14B. The optical fiber 7B is with the Cap 14B firmly connected. By means of an axial displacement of the closure cap (or, in the case of a design with a union nut, it can also be turned), the fiber end can be extended from the distal end of the cannula 3B by approximately 1 to after the insertion of the cannula with a pre-adjusted end of the fiber ending with the end of the cannula 2 mm into a scattering fluid depot created there beforehand.

4 shows, in a simplified longitudinal section, a further cannula or a catheter 3C for producing large-volume, elongated coagulation necrosis in body tissue 2. The catheter 3C has an outer catheter body 15C made of transparent plastic of essentially cylindrical shape, which is rounded at its distal end and is provided with openings 16C over a distal area of a few cm in length. Coaxial to the outer catheter body 15C, an inner glass cannula 17C is arranged in the interior 6C thereof, which extends almost to the distal end of the outer catheter body 15C and is also closed at its distal end. The outer catheter body has a laterally branching liquid supply 8C near its proximal end, which is closed with a plug 19C.

The glass cannula 17C receives an optical fiber 7C, which is provided in its end region of approximately 3 cm in length with a plurality of ring-shaped matting regions 18C, each of which is equidistant from one another. The optical fiber 7C is connected (which is not shown in the figure) at its proximal end to a laser radiation source. An elongated liquid depot IC surrounding the catheter end region is formed by the paraxial supply of medium to highly viscous scattering liquid via the feed line 8C, which is conducted into the surrounding tissue via the catheter interior 6C and the openings 16C. When laser radiation is subsequently supplied, it is coupled out sequentially or periodically on the matted rings and on the end face of the fiber 7C.

In connection with the marginal scattering fluid spot, it is possible for the first time and surprisingly to achieve an almost uniform distribution of the laser radiation over a longer cylindrical distance in the tissue without a considerable fluid volume of the biocompatible scattered light fluid. The prolongation of the scattered light application, which is thus possible for the first time according to the invention, at the same time allows higher laser powers to be applied, so that, for example, for the above-mentioned treatment of a prostate flap with a longitudinal extent of up to 5 cm and a diameter of 2 cm when applied from 15 to 20 W. Laser light power Radiation times of only 10 minutes are necessary to achieve the desired therapy result. The combination of paraxially supplied scattering fluid and laser radiation coupled in in the longitudinal direction of the catheter during the treatment ensures that the radiation, which in principle is periodically inhomogeneously scattered out of the fiber, is homogenized towards the surrounding tissue and thus becomes a calculable and even treatment result comes.

In FIG. 5, the inner cannula 17C with the optical fiber 7C according to FIG. shows. It can be seen how in the end region of the fibers freed from their cladding 21C and coating 22C there with an aspect ratio of 1: 1 each matted rings 18C and untreated fiber sections 20C alternate. The matted rings 18C have a decreasing diameter towards the end of the fiber or an increasing roughness depth. The glass cannula 17C, which is made clear or matt and can alternatively also consist of plastic (such as polycarbonate), is glued proximal to the matting area by an adhesive 23C with the coating 22C of the fiber and an MRI marker 24C encasing it.

FIG. 6 shows a modification of the arrangement shown in FIGS. 4 and 5. While the construction of the inner cannula and the optical fiber corresponds to that according to the figures mentioned and these are therefore also designated by the same reference numerals 17C and 7C as in FIG. 4, here is a closed catheter body 15D made of material that scatters the laser radiation intended. With this setup, a stray fluid depot can largely or possibly can also be dispensed with entirely, or the catheter can be inserted into a depot previously set by other means.

7 shows a possibility for producing the ring structure in the distal end region of the optical fiber 7C: the end of the base fiber which has been freed from coating and cladding is coated with rings L made of an acid-resistant lacquer (etching lacquer) and the fiber is used using a Control C, a motor M and a spindle holder Sp in the fiber longitudinal direction gradually in an etching liquid E. immersed where the surface of the fiber is etched in the uncoated areas. Since the residence time in the etching liquid decreases with increasing distance of the etched areas from the fiber end, the etching depth also decreases in this direction, whereby the desired course of the roughness depth or the effective fiber diameter is achieved. After the etching, the lacquer rings are removed.

The embodiment of the invention is not limited to the exemplary embodiments specified above. Rather, a number of variants are conceivable which make use of the solution shown, even in the case of fundamentally different types.

Claims

Expectations

1. Method for the thermal obliteration of biological tissue by means of laser radiation introduced into the tissue via an optical waveguide, the laser radiation being scattered over the means assigned to the radiation exit surface from the optical waveguide,

d a d u r c h g e k e n n z e i c h n e t that

around the exit surface of the radiation by injecting a biocompatible, medium to highly viscous liquid which does not essentially absorb the laser radiation but scatters it within the tissue, a scattering fluid depot which is not separate from it and which is used for the controlled heating of the tissue.

2. The method according to claim 1, dadurchge ¬ indicates that the liquid consists of an essentially transparent and a strongly light-scattering component and the components are injected into the tissue by means of a concentrically double-lumen cannula such that the transparent component on the inner and the strongly light-scattering component are introduced via the outer lumen, so that the strongly light-scattering component envelops the transparent component.

3. The method according to claim 2, dadurchge ¬ indicates that the laser radiation on the at the same time, the liquid column of the transparent component serving as an optical waveguide is introduced into the tissue in the inner lumen.

4. The method according to claim 4, so that the transparent component of the liquid is introduced into the inner lumen in at least overlapping time ranges and the laser radiation is injected.

5. The method as claimed in one of the preceding claims, that the viscosity of the liquid is adjusted in such a way that the scattering fluid depot remains essentially stable during the treatment period.

6. The method according to any one of the preceding claims, characterized in that the liquid comprises oil, water and glycerin, depending on the tissue to be sclerosed and the desired scattering properties 0.1 to 2% oil, 10 to 50% water and 50th up to 80% glycerin is included.

7. The method according to any one of claims 1 to 5, since ¬ characterized in that the liquid has a mixture of methyl cellulose and water, depending on the viscosity required tat and the scattering properties contain 1 to 30% water and 70 to 99% methyl cellulose.

8. The method according to any one of claims 2 to 7, characterized in that the transparent component glycerol and water, preferably in a mixing ratio of 80:20, and the strongly dispersing component oil and water, preferably in a proportion of 1 to 5% oil.

9. The method according to any one of the preceding claims, that the liquid has hyalaronic acid and / or intralipid.

10. The method as claimed in one of the preceding claims, that after injection of the liquid and formation of the scattering fluid depot, the optical waveguide is displaced in the distal direction by a predetermined amount into the scattering fluid depot after the liquid has been injected.

11. The method according to any one of the preceding claims, characterized in that the scattering fluid depot is formed in an elongated, in particular in a substantially ellipsoidal or cylindrical shape.

12. The method according to any one of the preceding claims, characterized in that the course of the temperature field propagation in the tissue is checked by continuous observation of the therapeutic area with a sonography device, with additional echoes depending on the temperature occurring in the area adjacent blood vessels when the here Temperature exceeds a value of 55 ° C and thus the C0 dissolved in the blood outgassing and further echoes occur if a temperature of 95 ° C in the aqueous component of the scattered light fluid creates intermediate water vapor.

13. The method according to any one of the preceding claims, that a x-ray contrast medium is added to the liquid and an x-ray observation is carried out.

14. Device for carrying out the method according to one of the preceding claims, characterized by a light waveguide arrangement which can be connected to a laser radiation source and is arranged in a lumen of a multi-lumen cannula and a device which is connected to at least one further lumen of the cannula for feeding a medium to highly viscous liquid.

15. The apparatus according to claim 14, dadurchge ¬ indicates that the cannula from essentially There are two subassemblies, one of which is the puncture cannula itself, which is to be inserted via a probing needle, and the second of which represents a fluid-tight Y-piece to be attached to this puncture cannula after removal of the probing needle, via which the fluid that scatters the laser light can be injected on the one hand and the fluid on the other the optical waveguide guiding the laser light is fixed in a pre-adjusted manner and can be advanced axially in a defined manner by means of a displacement mechanism.

16. The apparatus of claim 14 or 15, characterized in that the cannula is designed concentrically double-lumen, such that the inner lumen after flooding and injection of an optically transparent component of the scattering fluid itself serves as an optical waveguide and means for coaxial coupling of a fiber optic rule Optical waveguide are provided at the proximal end, while the outer lumen serves to supply the highly light-scattering component of the liquid.

17. The device as claimed in one of claims 14 to 16, that the cannula has a wall which does not substantially absorb the laser radiation.

18. Device according to one of claims 14 to 17, since - characterized in that the Licht¬ waveguide arrangement has an optical fiber whose Surface in a distal end section has a plurality of areas in the longitudinal direction successively matted, preferably ring-shaped, and that the end section is provided with a protective sheath that is transparent to the laser radiation.

19. The apparatus of claim 18, d a d u r c h g e - k e n n z e i c h n e t that the protective cover consists of a terminally closed and attached to the mechanically fixed part of the optical waveguide or the cannula precision glass or hard plastic capillary.

20. Apparatus according to claim 18 or 19, so that the matted areas have a roughness depth and / or a decreasing diameter towards the distal end of the optical fiber.

21. Device according to one of claims 14 to 20, d a - d u r c h g e k e n n z e i c h n e t that coaxial with the optical waveguide arrangement is provided a cladding tube that scatters the laser radiation and has openings for the exit of the liquid scattering the laser radiation into the tissue.